Leaked British government papers that outline the effect of a no-deal Brexit show the need for an orderly withdrawal by the UK from the EU, Government sources have said.

The documents, published by the Sunday Times, warn of a hard Irish border, a three-month “meltdown” at ports and shortages of food and medicine if the UK leaves the EU without a deal.

However, UK minister Michael Gove, in charge of co-ordinating no-deal preparations, played down the documents, saying they set out a worst-case scenario and that planning had been accelerated in the last three weeks.

Taoiseach Leo Varadkar is expected to speak to British prime minister Boris Johnson – who has promised the UK will leave the EU, deal or no deal, by October 31st – this week.

Mr Johnson is demanding that the backstop, the insurance policy to avoid a hard border, is abolished in order for there to be an orderly UK exit. He will also meet French president Emmanuel Macron and German chancellor Angela Merkel in the coming days.

The EU and Irish Government have consistently said the Brexit withdrawal agreement, which contains the backstop, will not be renegotiated.

The leaked documents were compiled this month by the UK cabinet office under the codename Operation Yellowhammer.

Unsustainable

Regarding Northern Ireland, the documents said the British government will activate “no new checks with limited exceptions” on day one of a no-deal Brexit but warn this will be unsustainable because of economic, legal and biosecurity risks. The papers warn this could lead to “direct action” and road blockades.

A Government source said the existing Brexit deal will avoid a hard border, adding: “These papers yet again underline the need for a managed Brexit, including the backstop insurance policy as set out in the withdrawal agreement.

“It is stated policy of the EU that in the case of no deal, peace and security on the Irish Border is key. Our teams are working with the European Commission on the twin objective of avoiding checks at the Border and maintaining Ireland’s place in our EU single market. However any solution that is found will be far inferior to the backstop and the all-island economy is going to be badly hit.”

The Sunday Times also reported a poll finding that almost 60 per cent of Northern Ireland voters supported the Northern Ireland-only backstop, an earlier version of the policy.

This kept Northern Ireland, rather than the entire UK, in a customs union with the EU, as well as aligned to the single market, as an insurance policy to avoid a hard border.

Backstop

Government sources pointed to these findings, saying “voters in Northern Ireland are showing that they overwhelmingly support the backstop”.

Fianna Fáil and Labour called on the Government to accelerate its own no-deal planning.

“Ministers have taken their foot off the pedal in terms of preparations for all Brexit outcomes and we are now playing catch up,”Fianna Fáil Brexit spokeswoman Lisa Chambers said, adding that the leaked documents “should act as a wake-up call to the very real possibility that the UK will crash out of the EU on October 31st and Ireland will be left reeling in the aftermath” .

Labour leader Brendan Howlin said: “It is essential that the Irish Government accelerate no-deal planning. Central to these preparations and missing to date has been the level of material support available for Ireland from the EU.”

A Government spokeswoman said: “Intensive no-deal planning continues apace, as set out in the latest contingency plan published by the Government last month.”